Issue 7, 2024

Oxidation of sulfides following anaerobic municipal wastewater treatment for non-potable reuse applications

Abstract

Anaerobic secondary biological wastewater treatment could increase energy efficiency by avoiding energy-intensive aeration while producing methane that could be harvested for energy production. However, sulfides produced by biological sulfate reduction can inhibit efforts to reuse wastewater by interfering with chlorine or UV disinfection. At laboratory- and pilot-scale, this study compared oxidation of sulfides in a pilot-scale anaerobic secondary effluent by hydrogen peroxide (H2O2) or chlorine (NaOCl) and disinfection by UV or NaOCl with respect to meeting water quality guidelines for non-potable reuse applications. Chlorine oxidized sulfides within 6 minutes but required high chlorine doses (∼200 mg-Cl2 L−1) and formed particulate elemental sulfur at pH ≥ 6.2, necessitating filtration. H2O2 oxidized sulfides within 24 min, forming elemental sulfur near pH 7 and thiosulfate at pH >8. UV disinfection at ∼200 mJ cm−2 average UV fluence achieved <2.2 MPN/100 mL total coliform and 5-log inactivation of bacteriophage MS2, while NaOCl disinfection only controlled total coliform. Initial cost estimates indicated that the lowest cost options (∼$0.40 per m3) to meet water quality goals for non-potable reuse involved sulfide oxidation either at pH 7 followed by filtration or at pH ∼8.3 without filtration, and then UV disinfection at 200 mJ cm−2 average UV fluence and addition of NaOCl to achieve a 5 mg-Cl2 L−1 total chlorine residual for distribution.

Graphical abstract: Oxidation of sulfides following anaerobic municipal wastewater treatment for non-potable reuse applications

Supplementary files

Article information

Article type
Paper
Submitted
09 Jan 2024
Accepted
26 Apr 2024
First published
30 Apr 2024

Environ. Sci.: Water Res. Technol., 2024,10, 1610-1622

Oxidation of sulfides following anaerobic municipal wastewater treatment for non-potable reuse applications

J. A. MacDonald, I. J. Tavarez and W. A. Mitch, Environ. Sci.: Water Res. Technol., 2024, 10, 1610 DOI: 10.1039/D4EW00012A

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